Fan flutter is a type of aerodynamic instability that occurs in a gas turbine engine fan when two or more adjacent fan blades vibrate at a frequency close to their natural frequency and the interaction between adjacent blades maintains and/or strengthens such vibration. Prolonged operation of a fan undergoing fan flutter can produce a potentially undesirable result caused by airfoil stress load levels exceeding threshold values. It is known in the field of gas turbine engine to mechanically mistune adjacent blades so as to separate their natural frequencies. Such a solution to fan flutter introduces however a level of manufacturing complexity that is not always desirable.
There is an ongoing need for mitigating fan flutter in a gas turbine engine fan.